Created attachment 196764 [details] v1 Boost tends to enable more features (including new libraries) for higher standards.
Can you do exp-run on 11.2 or later with make.conf from bug 229569 comment 9? If you plan to try on -CURRENT as well better use bug 230355 as both 11.2 and 12.0 have Clang 6.0.
I saw no new failure on 11.2 with the patch applied.
A commit references this bug: Author: jbeich Date: Sat Sep 8 00:53:11 UTC 2018 New revision: 479222 URL: https://svnweb.freebsd.org/changeset/ports/479222 Log: devel/boost-all: switch to C++17 on FreeBSD >= 11.2 PR: 231077 Exp-run by: antoine Changes: head/devel/boost-all/compiled.mk head/devel/boost-libs/Makefile head/devel/boost-python-libs/Makefile